Comparative study of the Catalytic Activity of Gold and Copper nanoclusters on Benzyl Alcohol oxidation to Benzaldehyde using Density Functional Theory

Density functional theory comparison of the role of Au and Cu on the catalysis of aerobic oxidation of benzyl alcohol to benzaldehyde was performed. Four metal clusters were analyzed, namely pure Au13 and Cu13 and doped Au12 Cu and Cu12 Au clusters. This study focuses on the previously reported minimum energy pathway for oxidizing two molecules of benzyl alcohol per adsorbed O2 . The reaction energy pathway diverges at the benzylic H abstraction step. For catalysts rich in Au, dissociation of O-O dissociation before this step is not required, conversely for Cu rich catalysts, O-O dissociation occurs prior to benzylic H abstraction step. The first transition state for the abstraction of alcoholic hydrogen by O2 presents a minimal energy barrier on the Au13 catalyst, while it is absent on the other three catalysts. The calculations exhibit that the reaction rate is primarily influenced by the adsorption of reactants and desorption of products, aligning with experimental findings. In Cu rich clusters, the adsorption of O2 is more favorable due to effective charge transfer between the cluster and O2 resulting in high adsorption energy. Additionally, the desorption of products is significantly endothermic on Cu rich catalysts, whereas it is exothermic on Au rich catalysts.